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Question DetailsAsked on 5/5/2011

I have an older house with plaster over wood instead of sheetrock. I'm doing some minor remodelling and am trying to have an electrical outlet in the bathroom moved to make way for a mirror. 2 companies so far refuse to do this because of the plaster. They are afraid the plaster will crack. Does anyone know how to do this? The electric comanies will move the outlet if I can have the hole cut myself. I don't have a lot of money and will be happy to do this myself if anyone has any suggestions or advice.

10 Answers

I'll tell you what I'd do and you can add mine to others' suggestions to see if a plan evolves.

First, I'd draw an outline on the plaster that I want to cut out. Then I'd get a very sharp bit for my electric drill and drill a hole in each corner. The hope is that a sharp bit will reduce the chance for creating stress and letting a crack form.

If you get all four corner holes drilled, then go half way on each line between holes and drill another. Keep this up until you have a bunch of holes along each line you had drawn then connect the holes. I'd either use that bit or a bit in a dremmel-like tool and go slow enough to not create tension on the plaster as you go 'round the outlet's opening.

With luck, you'll create the opening and not create cracking. With no luck, you will create a crack that you may have to get a plaster pro to stop 'n patch for you.

Dogmom, your home's interior walls are "lath & plaster". Great for climate control, but problemtatic. I have fond memories of our first home... interior walls were lath & plaster and exterior stucco was much thicker than the newer types. hammer a nail in a wall to hang a heavy mirror = hole the size of your thumb! stress cracks above doorways on load bearing walls were not uncommon. Homes of that era are well worth a little extra work.

If I remember correctly, on walls previously painted with severral coats of enamel, duct tape worked well to prevent the plaster from shattering into an uneven line. (used a saber saw??) Fishing new electrical wire to meet today's building codes (grounded) may be labor intensive - hire a electrican who is experienced and get a firm bid for the work to be performed

I am finally jumping in here because I know a thing or two about plaster. I think the companies you've contacted are just covering themselves in case the plaster cracks or breaks away, which it might do. If you want an electrical box installed I'd suggest contacting a plaster repair specialist, who can assess the actual condition of the plaster and will be used to making cuts in old plaster. Then either he or your electrician or handyman can put in the outlet box.

In England, most interior walls, even of new builds, are plaster. Older walls are the typical lathe-and-plaster that you are most likely dealing with. (Can you see the back of it from the attic or some other vantage point? It might be plaster over metal mesh if it's a more recent replaster job in that particular area.) Plaster has a lifespan and goes crumbly after a certain age, depending on the original constituents of the plaster itself, the way it was applied, and the ambient humidity over the years. That's why people are loathe to work on plaster, because you just never know what it's going to do. Also, it will eventually separate from the lathe behind it, and when that happens it is going to fall down sooner or later. I've seen plaster walls and ceilings cave in, and believe me if it's in that bad a shape you want it to happen under controlled conditions.

Sometimes when plaster is pulling away from the substrate - lathe or mesh - a professional can drill small holes very carefully and inject wet plaster to adhere it once more, but this is not a long-term solution and is also very expensive. However, if what you're dealing with are workmen who don't want the liability, then I'd get on the phone to a plaster repair person as I've already stated.

Under no circumstances should you follow any advice to make holes in the plaster yourself, by any means at all. Most homeowners who do that end up regretting it very deeply, because a "small" hole made in plaster can quickly become a large hole or an entire section cracking and/or breaking away. It costs either nothing or very little to get professional advice, and that is very much the best way to go with plaster.

As always, this is just one person's opinion and is probably worth what you paid for it.

Dogmom- OG's advice is a good one but what folks have forgotten to mention is that before you drill into anywall make sure you have an idea of where you existing power lines are behind the wall. Bad things can happen if drill into a live wire- electrocution, fire, or at the least a power outage caused by a short.

If you don't know or don't feel comfortable doing it hire an electrician- the expense is better than the risk-and as an aircraft mechanic who has been thrown off the wing of an F-16 by accidentally touching a live circuit trust me-- you don't want that pain!

If you have a electric stud finder sometimes they will also have wire and pipe finders and that may help you determine if you feel capable to do the hole yourself.

I came in at the end of the F4 days and only got to work a couple in Transit at Hill... old F4E Weasels... glad I neve had to work bomb racks on that bird! But I have many "Falcon Bites" to show where and when I gained "wisdom" on how not to do things... atleast the shock from the electricity numbed my body for the collision with the concrete! I didn't feel that till the next day when I woke up black and blue....

A good electrician can take this on, no problems. We also have an old Victorian and have done a TON of electric work. What my electrician and I do is to first mark the edges of where the box will be - then chisel an initial hole WELL INSIDE those lines.

Then use a dremel to make very exact cuts from the center hole out to the lines and follow them in sections and gently cut through the lath. The key is taking your time and using a high speed dremel with the proper masonry bit - so the material is cut and doesn't introduce any unnecessary vibration. Let the bit do the work! Plaster eats them up pretty quickly but you aren't doing a lot of work so one bit should do it. Then install an old work box - the metal tiger grip one's are best - as they will really grip inside the lath and the arms are long enough to get behind all that excess material.

The younger guys won't have a clue but a more seasoned older electrician will have experience with doing this right and avoiding any excessive vibration that will crack the plaster.

Hello I did historical plaster restoration at the Federal Court house in Indiana. To not have it crack at all is very tough. The best way is to mark out an outline the area to be removed with tape. Blue painters tape is the best for not removing the paint off the wall. Now use a box cutter knife to cut through the paint throught the finish coat and down to the brown coat. Once complete run your knife about at 45 degree angle or so towards the plaster you want removed because you want to be able to fit a chisle in the void to chip out the brown coat. Now for the tricky part =) This is where the plaster will mostly likely crack. The smaller the chisel the better. Sometimes drills with masonary bits work great they just don't get into the corners. Most people will make the mistake here use power tools that cause vibration which causes more damage to the wall. Pushing plus vibration will almost always cause an old plaster wall to crack somewhere. I had less cracks and damage with a chisle and knife than any other method.

I know this is an old thread, but contrary to some of the answers here, you can do a good job yourself if you take your time and don't use a heavy hand.

I have a house that was built in 1913 with plaster walls and I have done a lot of work to try to keep the walls intact. Plaster walls are beautiful and are good at soundproofing rooms, but they can be difficult to maintain. My preferred methods are a carbide scoring tool, as used with cement board, or my Dremel rotary tool with a carbide grouting bit.

My first step in creating a hole is using painter's tape to cover where I'm going to cut, followed by scoring the finish coat around the cut line. Then I delicately chip out the finish coat (from the interior of the area I want to remove) so I can get to the browncoat underneath. I score the browncoat down to the lath all around the hole, then I can chip out larger chunks without worrying too much about cracking the surrounding wall. I remove material on both sides of the lath, since the plaster on the back side is what provides the hold. Then I carefully cut the lath around the hole, which often doesn't cut cleanly due to age; if you aren't careful, moving the lath too much can cause cracking. Don't use a jigsaw - I know.

For a larger hole, I would use a Dremel or router with a carbide or diamond bit to score and cut the outline of the hole, as manually it is a lot of work. Drilling out the corners prior to scoring is a good idea and it's actually better if they aren't perfectly angles, to prevent future cracks from starting there.

The "old work" electrical boxes can work well. Just get them with clamps deep enough for your wall.

I use patching plaster (sometimes over a patch made from drywall board) to fill voids and mistakes and, optionally, Plaster of Paris for a finish coat. Joint compound or spackling paste is too soft to support anything but paint and will eventually fall out when used to fill a large space.